The present invention relates to bicomposite intraocular lenses (IOLs). More particularly, the intraocular lenses comprise a high water hydrogel optic portion and a relatively low water hydrogel haptic portion. In addition, the present invention is directed towards methods for manufacturing the bicomposite intraocular lenses.
The most commonly used material for IOLs has been polymethylmethacrylate (PMMA). However, PMMA lenses have been shown to be injurious to the corneal endothelium. The maintenance of corneal clarity is dependent on the endothelium which is essentially nonregenerative. It appears there is a biophysical interaction between the hydrophobic PMMA and the endothelium, such that even the slightest touch on insertion of the IOL will cause significant endothelial cell disruption by adherence of the cells to the lens surface.
U.S. Pat. No. 4,664,666 issued to Barrett, May 12, 1987, discloses a hydrophilic IOL. These lenses are formed of hydrogels which when are soft and flexible and have been found to cause little endothelial damage on contact. These IOLs, due to the mechanical properties of available hydrogel materials, are limited to configurations having flange type haptics rather than loop type haptics. However, the flange type haptics disclosed therein are not of a conventional loop type configuration; and as a result there can be difficulty in positioning and seating the lenses in the eye. The haptics can not be formed as conventional loop haptics due to the nature of the hydrogel material which is used for the entire IOL, including the optic portion and the haptic portion. If formed as loop haptics, the high water content haptics are not strong enough, or rigid enough, to support the optic portion of the IOL within the eye.
U.S. Pat. No. 4,242,762 issued to Tennant, Jan. 6, 1981 discloses IOLs wherein the haptic and the optic are preferaly manufactured as a single unit and formed of the same material. However, the optic may be formed of a different material and fused to the haptic. For example, Tennant discloses an optic formed of p-HEMA with the haptic being formed of PMMA. However, this IOL with its rigid haptic portion cannot be folded or deformed like the IOLs disclosed in U.S. Pat. No. 4,664,666. In addition, the use of PMMA haptics, like PMMA lenses, can be harmful to the corneal endothelium. U.S. Pat. No. 4,254,509 issued to Tennant, Mar. 10, 1981 discloses IOLs wherein the optic is made of a rigid material such as PMMA and the haptic portion is made of a soft material such as p-HEMA. U.S. Pat. No. 4,254,510 issued to Tennant, Mar. 10, 1981, discloses an IOL wherein the optic portion of the IOL may be of rigid material such as PMMA and the limbs or haptics can be made of PMMA or a softer material such as p-HEMA.
It is an object of the present invention to provide for IOLs which have the advantages of a hydrogel type lens, but with conventional loop type haptics that allow for proper positioning and seating of the IOL in the eye.
It is another object of this invention to provide methods for producing the lenses.